Systems and methods of water treatment for hydrogen production

ABSTRACT

A method includes providing raw water into a first filter assembly to remove solids from the raw water to form a filtrate, providing the filtrate from the first filter assembly into a second filter assembly to electrochemically remove ionics from the filtrate to form purified water, and providing the purified water to an electrolyzer to generate hydrogen by electrolyzing the purified water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/125,343, filed on Dec. 17, 2020, which claims the benefit of U.S.Provisional Patent Application No. 62/948,966, filed on Dec. 17, 2019,the entire contents of which are incorporated herein by reference.

FIELD

The present disclosure is directed to water treatment in general and,more specifically, to systems and methods of water treatment forhydrogen production.

BACKGROUND

Hydrogen is a common gas that has many uses, such as petroleum refining,metal treatment, food processing, and ammonia production. For industrialapplications, hydrogen is generally formed using processes requiringnon-renewable energy sources and, in particular, access to large amountsof natural gas and reliable sources water and grid power. However,because of its combustibility in air, hydrogen is difficult to store andship. For these reasons, hydrogen is generally used at or near the siteof its production which, in turn, is limited by the local availabilityof non-renewable energy sources.

SUMMARY

In one embodiment, a method includes providing raw water into a firstfilter assembly to remove solids from the raw water to form a filtrate,providing the filtrate from the first filter assembly into a secondfilter assembly to electrochemically remove ionics from the filtrate toform purified water, and providing the purified water to an electrolyzerto generate hydrogen by electrolyzing the purified water.

In another embodiment, a system comprises a water source, a first filterassembly in fluid communication with the water source, wherein the firstfilter assembly is configured to remove solids from raw water from thewater source to form a filtrate, an electrolyzer including an anode, acathode, and a proton exchange membrane between the anode and thecathode, and a second filter assembly in fluid communication between thefirst filter assembly and the electrolyzer, the filtrate from the firstfilter assembly flowable into the second filter assembly, the secondfilter assembly electrically energizable to remove ionics from thefiltrate to form purified water flowable to the anode of theelectrolyzer.

In another embodiment, a method comprises providing purified water froman electrically energizable filter assembly to a hydrogen productionsystem including an electrolyzer, providing power from a power source tothe electrolyzer to electrolyze the purified water in the electrolyzerto generate hydrogen, storing at least a portion of the generatedhydrogen in a hydrogen inventory, monitoring power availability from thepower source, determining a power requirement for the hydrogenproduction system, comparing the power requirement of the hydrogenproduction system to the power availability from the power source, andif the power requirement is less than the power availability, thengenerating power by a generator fueled by hydrogen from the hydrogeninventory, and providing the generated power to the electrolyzer tocontinue to generate the hydrogen.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a block diagram of a system of a first embodiment for watertreatment for hydrogen production, with the system including a firstfiltration system and a second filtration fed to an electrolyzeroperable to form hydrogen.

FIG. 1B is a schematic representation of the second filtration system ofFIG. 1A.

FIG. 1C is a schematic representation of the electrolyzer of the systemof FIG. 1A, with the electrolyzer including a proton exchange membrane(PEM) between an anode and a cathode.

FIG. 1D is a schematic representation of an ammonia synthesis reactor ofthe system of FIG. 1A, with the ammonia synthesis reactor including asynthesis cell activatable to form ammonia from hydrogen and nitrogen.

FIG. 1E is a schematic representation of an electrochemical cell of ahydrogen pump of the system of FIG. 1A.

FIG. 2A is a block diagram of a system of a second embodiment for watertreatment for hydrogen production, with the system including a hydrogeninventory and a generator operable with hydrogen inventory to provide anuninterruptible power supply for the system of water.

FIG. 2B is a block diagram of a power distribution of the system of FIG.2A.

FIG. 3 is a flowchart of an exemplary method for providinguninterruptible power to a system of water treatment for hydrogenproduction.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

The embodiments will now be described more fully hereinafter withreference to the accompanying figures, in which exemplary embodimentsare shown. The foregoing may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth herein. All fluid flows may flow through conduits(e.g., pipes and/or manifolds) unless specified otherwise.

All documents mentioned herein are hereby incorporated by reference intheir entirety. References to items in the singular should be understoodto include items in the plural, and vice versa, unless explicitly statedotherwise or clear from the text. Grammatical conjunctions are intendedto express any and all disjunctive and conjunctive combinations ofconjoined clauses, sentences, words, and the like, unless otherwisestated or clear from the context. Thus, the term “or” should generallybe understood to mean “and/or,” and the term “and” should generally beunderstood to mean “and/or.”

Recitation of ranges of values herein are not intended to be limiting,referring instead individually to any and all values falling within therange, unless otherwise indicated herein, and each separate value withinsuch a range is incorporated into the specification as if it wereindividually recited herein. The words “about,” “approximately,” or thelike, when accompanying a numerical value, are to be construed asincluding any deviation as would be appreciated by one of ordinary skillin the art to operate satisfactorily for an intended purpose. Ranges ofvalues and/or numeric values are provided herein as examples only, anddo not constitute a limitation on the scope of the describedembodiments. The use of any and all examples or exemplary language(“e.g.,” “such as,” or the like) is intended merely to better illuminatethe embodiments and does not pose a limitation on the scope of thoseembodiments. No language in the specification should be construed asindicating any unclaimed element as essential to the practice of thedisclosed embodiments.

Co-locating hydrogen production with its ultimate industrial use ischallenging in resource constrained areas. In particular, theinfrastructure for purified water in such areas is typicallyinsufficient or unreliable for producing cost-effective quantities ofhydrogen, and the electrical infrastructure for powering water treatmentis often similarly limited. Accordingly, there remains a need forreliable water treatment that can produce purified water in quantitiescompatible with large-scale hydrogen production while being robust withrespect to interruptions in access to raw water and/or power used in thepurification process. In the description that follows, various aspectsof water treatment systems and methods for hydrogen production aredescribed in the context of ammonia production, as ammonia production isa common use for hydrogen and offers certain synergies with respect tothe various different systems and methods described herein. It shall beappreciated, however, that this is for the sake of explanation ofcertain features of the systems and methods described herein and shouldnot be considered limiting. That is, unless otherwise specified or madeclear from the context, it shall be understood that any one or more ofthe various different systems and methods described herein may becompatible with any one or more hydrogen end-use applications. By way ofexample and not limitation, such hydrogen end-use applications mayinclude use in a forming gas for a reducing environment, as described inU.S. patent application Ser. No. 17/122,813, filed on Dec. 15, 2020,entitled “SYSTEMS AND METHODS OF ELECTROCHEMICAL HYDROGEN GENERATION TOPROVIDE A REDUCING AMBIENT FOR INDUSTRIAL FABRICATION” by Ballantine etal., the entire contents of which are incorporated herein by reference.

As used herein, the term “raw water” shall be understood to includewater of quality unsuitable for prolonged operation in anelectrochemical electrolyzer operated to form hydrogen. Thus, forexample, raw water may include water that has been contaminated by humanuse (commonly referred to as wastewater), some examples of which includewater used in domestic, commercial, and/or industrial settings. Furtheror instead, wastewater may include stormwater and/or sewer inflow. Insome cases, raw water may include city water, water from atmosphericcondensation, or a combination thereof. In some cases, raw water mayinclude water from a natural body of water, such as a nearby lake,river, or ocean. Thus, raw water may be fresh water or seawater. Unlessotherwise specified or made clear from the context, it shall beunderstood that any one or more of the various systems and methodsdescribed herein may facilitate treating any or more of the foregoingexamples of raw water to form purified water. In one sense, as usedherein the term “purified water” may be understood in relative terms, asmay be useful in discussing of any one or more aspects of the overallfiltration process. For example, purified water may include water of anyquality, provided that such water has a lower concentration of totalsolids (e.g., suspended and/or dissolved solids), a lower concentrationof organics (e.g., microbiologics, such as bacteria, etc.) and/or lowerconcentration of at least one ionic contaminant as compared to the rawwater used as the starting material in a given overall filtrationprocess (which may have multiple stages). In another sense, as usedherein, the term “purified water” may be understood in absolute terms,as may be useful in discussing any one or more aspects of electrolyzers,hydrogen pumps, fuel cells, etc. that may be sensitive to water quality.Thus, for example, purified water may include water of any qualitycompatible with operation of an electrochemical cell as an electrolyzerover a prolonged period of time (e.g., greater than about 12 hours)without interruption.

Referring now to FIGS. 1A-1E, a system 100 may include a water source102, a first filter assembly 104, a second filter assembly 106, and anelectrolyzer 108. The water source 102 (e.g., a raw water reservoirand/or pipe) may be in fluid communication with the first filterassembly 104 via a raw water conduit 110. The second filter assembly 106may be in fluid communication between the first filter assembly 104 andthe electrolyzer 108. For example, the second filter assembly 106 mayreceive a filtrate from the first filter assembly 104 via a filtrateconduit 112, and the electrolyzer 108 may receive purified water fromthe second filter assembly 106 via a purified water conduit 114. Forexample, the first filter assembly 104 may generally remove solids fromthe raw water to form the filtrate flowable to the second filterassembly 106 via filtrate conduit 112. Additionally, or alternatively,the second filter assembly 106 may include one or more components thatare electrically energizable to remove ionics (i.e., ionic impuritiesand/or contaminants, such as cations (e.g., metal ions) and/or anions(e.g., chlorite ions, bromate ions, arsenate ions, etc.)) from thefiltrate to form the purified water flowable to the electrolyzer 108 viathe purified water conduit 114. The electrolyzer 108 may receive powerfrom a power source 115 to electrolyze water to hydrogen. As describedin greater detail below, water filtration carried out by the firstfilter assembly 104 and the second filter assembly 106 may be tightlyintegrated with hydrogen production carried out using the electrolyzer108 such that the system 100 is robust with respect to interruptions ina supply of raw water from the water source 102. Further, or instead, asalso described in greater detail below, integration between the firstfilter assembly 104 and the second filter assembly 106 may be robustwith respect to interruptions in a supply of power to the electrolyzer108 from the power source 115. Among other things, such robustness mayfacilitate sourcing power for the power source 115 from one or moresources of renewable energy to produce industrial quantities of hydrogencost-effectively while being environmentally responsible.

In general, the first filter assembly 104 may include any one or more ofvarious different types of equipment for removing solids from raw waterreceived from the water source 102. For example, the first filterassembly 104 may include filter media 116. As raw water passes throughthe filter media 116 solids in the raw water may be physically separatedfrom the water by restrictions in the filter media 116. As an example,the filter media 116 may include a sand bed, as may be useful ininstances in which the composition of the raw water at a giveninstallation may be prone to varying over time. Further or instead, thefilter media 116 may include a specifically designed filter useful forremoving solids with specific characteristics associated with a knownsource of raw water. In some instances, the filter media 116 may bereusable through washing and/or regeneration. However, in some cases,the filter media 116 may be disposable to reduce the amount of skilledlabor required to operate the system 100. In addition to, or instead of,the use of filtration to remove solid particles, the first filterassembly 104 may carry out any one or more of various different othertechniques for separating solids from the raw water. Examples of suchtechniques include, but are not limited to, sedimentation, dissolved airflotation, coagulation for flocculation, coagulant aids, or combinationsthereof.

In some instances, the first filter assembly 104 may be passive suchthat the flow of raw water through the first filter assembly 104 isgenerally throttled only by pressure drop the first filter assembly 104.Such a configuration may be useful, for example, for operating the firstfilter assembly 104 without the use of external power. In installationsin which power interruptions are frequent and/or of long duration,operating the first filter assembly 104 without the use of power may beuseful with respect to the overall power budget of the system 100.

While operating the first filter assembly 104 without the use of powermay have certain advantages in some installations, it shall beappreciated that the first filter assembly 104 may be advantageouslyinclude one or more aspects of active control by electronicallyactivated equipment in some cases. For example, the first filterassembly 104 may include one or more valves 118 electrically actuatableto control (e.g., interrupt, reduce and/or increase) the flow of rawwater through the first filter assembly 104 and, thus, to downstreamcomponents. Such control of the flow may be useful for, among otherthings, interrupting the flow of water to replace and/or regenerate thefilter media 116 without interrupting operation of the electrolyzer 108,as described in greater detail below. The remaining residue (i.e., waterwith contaminants) may be recycled via the recycling conduit 119 fromthe first filter assembly 104 and/or the second filter assembly 106 backinto the water source 102 or the raw water conduit 110, or it may bediscarded.

In general, the second filter assembly 106 may include any one or moreof various different types of filtration equipment electricallyenergizable to remove ionics from the filtrate received into the secondfilter assembly 106 via the filtrate conduit 112. As used in thiscontext, electrically energizable may include electrochemical removal ofionics, electrical actuation of pressure-driven processes, orcombinations thereof. Thus, for example, as shown in FIG. 1B, the secondfilter assembly 106 may include an electrodialysis cell 120 electricallyactuatable to remove salts from the filtrate. As another example, thesecond filter assembly 106 may include an electrooxidation cell 122,which may be electrically actuated to remove contaminants, such asindustrial effluents, that may be present in the filtrate. Further, orinstead, the second filter assembly 106 may include a reverse osmosisreactor 124, in which electrical actuation may include moving a pistonto apply pressure to the filtrate until the pressure applied to thefiltrate is sufficient to overcome osmotic pressure and move thefiltrate through a permeable membrane. The contaminants removed byreverse osmosis reactor 124 may depend, for example, on the permeabilityof the membrane, with salts and biological material being removable insome cases.

The treatment of the filtrate flowing through the filtrate conduit 112is shown as occurring in a particular order in FIG. 1B, with theelectrodialysis cell 120 followed by the electrooxidation cell 122followed by the reverse osmosis reactor 124. However, it shall beappreciated that this is for the sake of clear and efficient descriptionand the order of processing in the second filter assembly 106 may occurin any order, and need not be sequential, as may be useful for achievingreduction in concentration of ionics in the filtrate while makingefficient use of the energy used to electrically energize the secondfilter assembly 106. More generally, it shall be appreciated that thesecond filter assembly 106 may accommodate reduction in ionics in thefiltrate formed from any sources of raw water available to be used bythe system 100 while achieving such reduction within a power budgetafforded by other equipment of the system 100 also directly, orindirectly, being powered by the power source 115.

Filtration effectiveness of one or more portions of the second filterassembly 106 may degrade over time as ionics are removed from thefiltrate to produce purified water. In some cases, such as in the caseof the reverse osmosis reactor 124, performance may be restored byreplacing the permeable membrane, for example. In the case ofelectrochemical removal components of the second filter assembly 106,electricity may be advantageously used to recover filtrationeffectiveness without the need to access or otherwise disturb theinstallation of the given component. As an example, the electrodialysiscell 120 may be flushed with purified water. With potential toelectrodes of the electrodialysis cell 120 reversed, such flushing withpurified water may drive accumulated impurities off of the electrodeduring a maintenance procedure. Performance of the electrooxidation cell122 may be similarly recovered through reversal of polarity ofelectrodes while the electrooxidation cell 122 is flushed with purifiedwater.

While all of the purified water formed by the second filter assembly 106may flow from the second filter assembly 106 to the electrolyzer 108, itmay be useful to divert at least a portion of the purified water into asupplemental water conduit 128 and into a water inventory 126 for anyone or more of various different reasons. For example, in some cases, acontrol valve 129A may be selectively actuatable based on a state offlow of purified water from the second filter assembly 106. For example,under normal operating conditions, the control valve 129A may beactuated to divert purified water to the water inventory 126.Additionally, or alternatively, returning to the example of flushingdiscussed above, the control valve 129A may be selectively actuatable todirect purified water from the water inventory 126 to the second filterassembly 106.

In some cases, the water inventory 126 may serve as a backup source ofpurified water in the event that filtration of raw water from the watersource 102 is interrupted or wanes as a result of correspondinginterruptions and/or fluctuations of the raw water of the water source102, energy produced by the power source 115, cleaning or repair of thefirst or second filter assemblies, or a combination thereof. That is, inthe event of an interruption to the flow of purified water from thesecond filter assembly 106 for any reason, the control valve 129A may beselectively actuatable to direct the purified water stored in waterinventory 126 (e.g., in the excess pure water module (e.g., waterstorage vessel) 130) to the electrolyzer 108 to sustain uninterruptedoperation of the electrolyzer 108 for a period of time until the supplyof raw water from the water source 102 and/or electricity from the powersource 115, as the case may, returns to a level sufficient to supportfiltration of purified water. Given this robustness with respect tointermittency, the water inventory 126 may facilitate includingrenewable photovoltaic and/or wind power sources in the power source115. That is, continuing with this example, these intermittent powersources may be used to power at least the second filter assembly 106directly (e.g., with little or no battery) such that purified water isdirected to the water inventory 126 when renewable power is available.When such renewable power is unavailable or in the event of a poweroutage in cases of energy source from the grid, the purified water inthe water inventory 126 may be used as a source of purified water forthe electrolyzer 108, ammonia synthesis, or other consumer use (e.g.,drinking or cooking). In certain instances, the water inventory 126 mayadditionally, or alternatively, include a heated water module (e.g., aheated and/or thermally insulated water storage vessel) 132. The heatedwater module 132 is supplied with purified water heated by theelectrolyzer 108 through a heated water conduit 131. The flow of heatedwater through the heated water conduit 131 may be controlled by anotherselectively actuatable control valve 129B. Such water may be useful, forexample, for certain consumer uses.

In general, the electrolyzer 108 may include at least one instance of anelectrochemical cell shown in FIG. 1C. For example, the electrolyzer 108may include an anode 134, a cathode 136, and a medium 138 therebetween.The medium 138 may include any one or more of various different protonexchange media (e.g., electrolyte) and, in particular, may include apolymer proton exchange membrane (PEM). Purified water introduced intothe electrolyzer 108 via the purified water conduit 114 may flow alongthe anode 134. Electricity input from the power source 115 (e.g.,directly and/or via a battery) may be coupled to the anode 134 and thecathode 136 to form an electric field across the medium 138. Thepurified water may be separated into oxygen and pressurized hydrogen inthe presence of the electric field across the medium 138. Morespecifically, oxygen may be formed along the anode 134, and pressurizedhydrogen may be formed along the cathode 136 as protons move through themedium 138 and recombine into molecular hydrogen along the cathode 136.Thus, the cathode 136 may be in fluid communication with any one or moreof various different downstream applications, via a hydrogen conduit 140shown in FIG. 1A, such that the pressurized hydrogen formed from onlywater and electricity may be delivered to the downstream application ona continuous basis. As described in greater detail below, in instancesin which the system 100 is used to provide hydrogen for ammoniasynthesis, at least a portion flowing along the hydrogen conduit 140 mayflow to an ammonia synthesis reactor 150 shown in FIG. 1A.

To facilitate forming purified water through efficient use of energy,the system 100 may include a first oxygen conduit 142 in fluidcommunication between the electrolyzer 108 and the water source 102.Continuing with this example, the oxygen-enriched water flowing alongthe anode 134 of the electrolyzer 108 may flow to the water source 102(and/or to the raw water conduit 110) via the first oxygen conduit 142.This oxygen-enriched water may be useful in the water source 102 toenhance bacterial water clean-up. Under otherwise identical conditions,this may reduce one or more filtration demands on the first filterassembly 104 and/or the second filter assembly 106 and, in some cases,may reduce the power consumption associated with filtration to formpurified water.

Having described certain aspects of the system 100 for treating waterfor hydrogen production, attention is now directed to certain additionalor alternative features of the system 100 that may be useful for, amongother things, achieving suitable control over various different aspectsof coordination of processes carried out by the system 100, makingbeneficial use of the hydrogen produced, and/or reducing the likelihoodof premature degradation of elements of the system 100.

In some instances, the system 100 may include a controller 144 includinga processing unit 146 and a non-transitory, computer-readable storagemedium 148 having stored thereon computer-readable instructions forcausing the processing unit 146 to carry out any one or more of thevarious different techniques described herein. For example, returning tothe discussion of the water inventory 126 above, the controller 144 maycontrol the selective actuation of the control valves 129A and/or 129Bto direct purified water into and out of the water inventory 126 asuseful for increasing the likelihood of sustaining hydrogen productionduring interruption of one or both of raw water and/or power. Asdescribed in greater detail below, operation of the controller 144 andother electrically powered aspects of the system 100 may be sustainedthrough the use of a back-up power source such as a battery and/or agenerator fueled with hydrogen from a hydrogen inventory.

In certain instances, the system 100 may include an ammonia synthesisreactor 150 and a nitrogen source 152. The ammonia synthesis reactor 150may receive hydrogen via the hydrogen conduit 140. The ammonia synthesisreactor 150 may be in fluid communication with the electrolyzer 108 andthe nitrogen source 152. In particular, the nitrogen source 152 mayproduce nitrogen that is flowable to the ammonia synthesis reactor 150via a nitrogen conduit 154. With these hydrogen and nitrogen inputs andpower from the power source 115, the ammonia synthesis reactor 150 mayform ammonia. For example, the ammonia synthesis reactor 150 may formammonia through electrochemical synthesis, such as described in U.S.patent application Ser. No. 17/101,224, filed on Nov. 23, 2020, entitled“SYSTEMS AND METHODS OF AMMONIA SYNTHESIS,” by Ballantine et al., theentire contents of which are incorporated herein by reference.

In certain instances, the ammonia synthesis reactor 150 may include anelectrochemical cell, such as a synthesis cell 155 (e.g., aproton-exchange membrane (“PEM”) cell) operable for electrochemicalsynthesis of ammonia from hydrogen and nitrogen. The synthesis cell 155may include an anode 156, a cathode 157, and a medium (e.g.,electrolyte) 158, as shown in FIG. 1D. The medium 158 may be disposedbetween the anode 156 and the cathode 157 and, for example, may beionically conductive to protons. As a more specific example, the medium158 may be a proton-exchange membrane electrolyte. Additionally, oralternatively, the synthesis cell 155 may receive power from the powersource 115 connected to the anode 156 and to the cathode 157 to createan electric field in the medium 158 disposed between the anode 156 andthe cathode 157 (to apply a voltage between the anode 156 and thecathode 157).

The hydrogen introduced into the ammonia synthesis reactor may flow overthe anode 156, where the hydrogen may break down into protons accordingto the following reaction:

3H₂→6H⁺+6e ⁻

In turn, under the electric field provided by the power source 115, theprotons may flow from the anode 156 to the cathode 157 through themedium 158. The nitrogen introduced into the ammonia synthesis reactor150 may flow over the cathode 157, where the nitrogen may react with theprotons to form ammonia according to the following reaction:

N₂+6H⁺+6e ⁻→2NH₃

While the ammonia synthesis reactor 150 has been described as includinga single instance of the synthesis cell 155, it shall be appreciatedthat this is for the sake of clarity and efficient description. Morespecifically, the ammonia synthesis reactor 150 may include additionalinstances of the synthesis cell 155 (e.g., as part of an electrochemicalstack) without departing from the scope of the present disclosure. Thenumber of additional instances of the synthesis cell 155 may depend, forexample, on desired ammonia output from the system 100. While theammonia synthesis reactor 150 has been described as including anelectrochemical cell, it shall be appreciated that the ammonia synthesisreactor 150 may include a catalyst (e.g., a catalyst operated in aHaber-Bosch processes) or a plasma-driven reactor.

The nitrogen source 152 may include a pressure swing adsorber thatseparates nitrogen from air using pressure swing adsorption, producingnitrogen-depleted air as a byproduct. In some instances, the nitrogensource 152 may be in fluid communication with the water source 102 todirect nitrogen-depleted air to the water source 102 (e.g., via a secondoxygen conduit159). This nitrogen-depleted—and thus oxygen enriched—airmay enhance bacterial cleanup of the raw water in the water source 102.

In some implementations, the system 100 may include a hydrogen pump 160.Operation of the hydrogen pump 160 may, for example, re-establishhumidification conditions of the medium 138 of the electrolyzer 108 ininstances in which the medium 138 includes a proton exchange membrane.For example, the hydrogen pump 160 may be operable (e.g., via control bythe controller 144) to pump hydrogen from the anode 134 to the cathode136, cathode 136 to anode 134, or both in a sequence of fully humidifiedvolumes.

In certain implementations, the hydrogen pump 160 may be anelectrochemical membrane hydrogen pump which includes at least oneinstance of an electrochemical cell 161, as shown in FIG. 1E. For thesake of clarity of illustration and description, a single instance ofthe electrochemical cell 161 is shown. However, it shall be appreciatedthat the hydrogen pump 160 may include additional electrochemical cellsin other instances, without departing from the scope of the presentdisclosure. The total number of electrochemical cells in the hydrogenpump 160 may be influenced by, among other considerations, the pressurerequired to move hydrogen from the hydrogen conduit 140, via therecirculation circuit 162.

The electrochemical cell 161 may include a proton exchange membrane 163,an anode 164, and a cathode 165. For example, the proton exchangemembrane 163 may be disposed between the anode 164 and the cathode 165.Electrical power may be delivered to the anode 164 and the cathode 165by the power source 115 to provide a positive charge along the anode 164and a negative charge along the cathode 165. The resulting electricalfield may result in a higher pressure concentrated along the cathode 165than along the anode 164. As an example, at the anode 164, lowerpressure hydrogen may separate into protons and electrons, and theelectrical field may drive protons across the proton exchange membrane163 to the cathode 165. Continuing with this example, the protons mayrecombine at the cathode 165 to form hydrogen at a higher pressure. Asmay be appreciated from the foregoing, sequential pumping of hydrogenmay be repeated using as many instances of the electrochemical cell 161as necessary or desirable to remove hydrogen from the hydrogen conduit140 and electrochemically pump the removed hydrogen to a target pressurefor reintroduction back into the electrolyzer 108.

Having described various aspects of the system 100 that are electricallypowered by the power source 115, attention is now directed to certainaspects of the power source 115 operable to provide electricitysupporting any one or more of the various different aspects of thesystem 100 described herein.

In addition to uninterrupted operation facilitated by various differentredundancies with respect to water and power described herein,cost-effective operation of the system 100 may be a function of thepower source 115 that provides electricity to various differentcomponents of the system 100. For example, the power source 115 mayinclude multiple types of electricity generators that may beadvantageously operated in parallel and/or individually at differenttimes of the day. For example, in certain installations, the powersource 115 may include the electrical grid and, even in locations inwhich the electrical grid is reliable, it may be useful to switch tolocal sources of electricity to make use of lower-cost electricity.Examples of such local sources include, but are not limited to, one ormore of a diesel generator, a natural gas-fired generator, a generatorpowered by biofuel sources such as bio-methane, an ethanol firedgenerator, a gasoline fired generator, a propane fired generator, aphotovoltaic array, a wind power generator (e.g., one or more windturbines), a hydroelectric generator or turbine (e.g., tidal or damtype), a geothermal power generator, a thermoelectric power generator, aheat engine (e.g., a turbine, piston engine, or other engine which usesheat and/or fuel as an input), or a fuel cell power generator.

As may be appreciated from these foregoing examples, the power source115 may include local sources that are nominally continuous and/orintermittent. Thus, in the case of intermittent electricity availabilityfrom a local source such as a photovoltaic array or a wind turbine, thepower source 115 may preferentially be the local source when power fromthe local source is available without separate storage. Additionally, oralternatively, the system 100 may include a battery, as described ingreater detail below, in electrical communication with the power source115 and at least the second filter assembly 106 and the electrolyzer 108of the system 100, such as may be useful for managing variations inpower from one or more intermittent power sources by storing excesspower from the local source when the excess power is available (e.g.,during daytime from a photovoltaic array or during windy periods from awind turbine) and then releasing it to the plurality of cores when theexcess power is not available (e.g., during nighttime or during windlessperiods). As another example, in certain locations, the electrical gridmay be unreliable or nonexistent such that the power source 115primarily or exclusively includes any one or more of various differentlocal sources, such as those listed above.

As may be appreciated from the foregoing, the power source 115 may beintermittent as a result of the mix of local power generation sourcesthat make up the power source 115, resource constraints in the vicinityof the system 100, or a combination thereof. Accordingly, attention isnow directed to certain aspects of systems and methods that mayfacilitate uninterrupted operation of certain functions of the systemand, in particular, may be useful for the cost-effective production ofhydrogen using one or more renewable energy sources that may be prone tointermittency. For the sake of clear and efficient description, elementshaving numbers with the same last two digits shall be should beunderstood to be analogous to or interchangeable with one another,unless otherwise explicitly made clear from the context and, therefore,are not described separately from one another, except to notedifferences or emphasize certain features. Thus, for example, theelectrolyzer 108 of FIGS. 1A and 1C shall be understood to be analogousto the electrolyzer 208 of FIGS. 2A and 2B, unless otherwise indicatedor made clear from the context.

Referring now to FIGS. 2A and 2B, a system 200 may include a watersource 202, a first filter assembly 204, a second filter assembly 206,and an electrolyzer 208. Raw water in the water source 202 may be formedinto purified water delivered to the electrolyzer 208 according to anyone or more of the various different techniques described herein.Further, or instead, the system 200 may include a water inventory 226operable in a manner analogous to the water inventory 126 discussedabove with respect to FIG. 1A to facilitate sustaining hydrogenproduction through interruptions in a supply of raw water.

In certain implementations, the system 200 may include a hydrogeninventory 266 and a generator 267. The hydrogen inventory 266 may be ahydrogen storage vessel, such as at least one gas storage tank orcylinder. In general, the hydrogen inventory 266 may be in fluidcommunication with the electrolyzer 208 to receive hydrogen from theelectrolyzer 208. For example, a first hydrogen valve 268 may beselectively actuatable (e.g., by a controller 244 including a processingunit 246 and a non-transitory computer-readable storage medium 248) todirect at least a portion of the hydrogen flowing from the electrolyzer208 to the hydrogen inventory 266 via a first hydrogen supply conduit269. For example, during normal operation, the first hydrogen valve 268may be controlled to direct a portion of the hydrogen from theelectrolyzer 208 to the hydrogen inventory 266, with the remainder ofthe hydrogen moving along a hydrogen conduit 240 to be used according toany one or more of various different end-uses described herein.Additionally, or alternatively, the first hydrogen valve 268 may beselectively actuatable to stop the flow of hydrogen to the hydrogeninventory 266 in the event of an interruption of electricity from apower source 215 providing electricity to various different aspects ofthe system 100 during normal operation. That is, during an interruptionof power from the power source 215, the first hydrogen valve 268 may beactuated to direct all of the hydrogen produced by the electrolyzer 208to an end-use application to reduce the likelihood of interruptinghydrogen production in a way that might cascade to the end-use of thehydrogen. Additionally, or alternatively, in the event of interruptionof electricity from the power source 215, fluid communication betweenthe hydrogen inventory 266 and the generator 267 may be establishedalong a second hydrogen supply conduit 270 via selective actuation of asecond hydrogen supply valve 271.

With fluid communication established between the hydrogen inventory 266and the generator 267 when power from the power source 215 isinterrupted, the generator 267 may operate on hydrogen from the hydrogeninventory 266 to provide power to sustain operation of at least one ofthe first filter assembly 204, the second filter assembly 206, or theelectrolyzer 208. For example, in certain implementations, the generator267 may sustain operation of the first filter assembly 204 and thesecond filter assembly 206 to continue producing purified water that maybe used by the system 200. Additionally, or alternatively, the generator267 may power the electrolyzer 208 to allow the electrolyzer 208 tocontinue making hydrogen while power from the power source 215 isinterrupted. In some cases, the electrolyzer 208 may continue to producehydrogen using purified water from the water inventory 226. Further, orinstead, the electrolyzer 208 may continue to produce hydrogen usingpurified water as it is being produced by the second filter assembly206.

In general, the generator 267 may be any one or more of variousdifferent energy sources operable to produce electricity from hydrogen.Thus, in some instances, the generator 267 may include an internalcombustion engine. Further, or instead, the generator 267 may include afuel cell (e.g., a proton exchange membrane fuel cell). In suchinstances, a water supply line 272 may couple the water inventory 226 influid communication with the generator 267 such that water from thewater inventory 226 may be delivered to the generator 267. While thegenerator 267 may be sized to provide power for at least waterpurification and/or hydrogen production via electrolysis, it shall beappreciated that the generator 267 may be sized to support operation ofone or more other types of equipment (e.g., ammonia synthesis) duringpower interruption to reduce the likelihood of cascading interruptionsof downstream processes.

In some cases, the system 200 may further include a battery 273 inelectrical communication with the generator 267, which may be useful forproviding energy storage providing a buffer for operation of equipmentthat may have surges in demand. Additionally, or alternatively, to theextent the power source 215 includes DC renewable power sources, thebattery 273 may be in electrical communication with the power source215, as described in greater detail below with respect to FIG. 2B.

FIG. 3 is a flow chart of an exemplary method 390 for providinguninterruptible power to a system of water treatment for hydrogenproduction. Unless otherwise specified or made clear from the context,the exemplary method 390 may be implemented using any one or more of thevarious different systems, and components thereof, described herein.Thus, for example, the exemplary method 390 may be implemented ascomputer-readable instructions stored on the non-transitorycomputer-readable storage medium 248 and executable by the processingunit 246 of the controller 244 to operate the system 200, as shown inFIG. 2A.

As shown in step 391, the exemplary method 390 may include monitoringpower availability from a power source. Such monitoring may include, forexample, monitoring power availability from the power source inreal-time, such as through measurement of voltage and/or current at oneor more points in the power source. As a specific example, monitoringpower availability from the power source may include detecting an outageas the outage occurs, such as may be achievable using one or moreswitches and/or sensors. In some cases, monitoring may further orinstead include predictions of power availability, such as based on pastfluctuations and/or environmental conditions known to impact powergeneration by the power source.

As shown in step 392, the exemplary method 390 may include determining apower requirement for a hydrogen system, such as any one or more of thevarious different hydrogen production systems described herein. Thus, inparticular, the hydrogen production system may include at least anelectrolyzer receiving purified water from an electrically energizablefilter assembly.

As shown in step 393, the exemplary method 390 may include comparing thepower requirement of the hydrogen production system to poweravailability from the power source. In general, this comparison mayserve as a basis for whether or not to use a hydrogen fueled generatorand/or the battery as a power supply to sustain operation of thehydrogen production. The hydrogen fueled generator may include, forexample, the generator 267 in FIG. 2A and thus may be a generator fueledby hydrogen output from an electrolyzer (e.g., hydrogen stored in ahydrogen inventory). Further, or instead, the hydrogen fueled generatormay be operable to convert hydrogen into power for operation of theelectrolyzer.

As shown in step 395, the exemplary method 390 may include generatingpower at the generator if the power available from the power source isless than the power required for operation of the hydrogen productionsystem to produce hydrogen (with a margin of safety applicable in someinstances). Additionally, or alternatively, generating power at thegenerator may include controlling a flow of hydrogen into a hydrogeninventory from the electrolyzer and out of the hydrogen inventory to thegenerator. As a specific example, such control may include interruptingflow of hydrogen into the hydrogen inventory from the electrolyzer whileestablishing a flow of hydrogen out of the hydrogen inventory to thegenerator. That is, all of the hydrogen produced by the system while thegenerator is operable may be directed out of the system, thus reducingthe likelihood that hydrogen demands of the end-use application will notbe met.

In instances in which the generator includes a fuel cell powergenerator, generating power at the generator may include controlling aflow of purified water from the electrically energizable filter assemblyinto a water inventory and controlling the flow of purified water fromthe water inventory to the generator. In particular, such control mayinclude interrupting a flow of purified water from the electricallyenergizable filter assembly into the water inventory while establishinga flow of purified water from the water inventory to the generator.

As shown in step 396, the exemplary method 390 may checking whether ashutdown condition is appropriate and shutting down if so. Otherwise,the exemplary method 390 may continue to repeat any one or more of thesteps described above as part of a continuing monitoring process usefulfor reducing the likelihood of disruption to a hydrogen productionprocess in the event of intermittent availability of electricity.

Having described various aspects of systems and methods useful foravoiding or mitigating disruptions in one or both of water orelectricity inputs to hydrogen production, attention is now directed tocertain aspects of power distribution that are useful in any one or moreof the various different systems described herein.

Referring again to FIG. 2B, the system 200 may include a common directedcurrent (DC) bus 274 (e.g., a 400 V bus or another suitable voltage bus)in electrical communication with power electronics 275 (e.g., fullyisolated such that ground faults do not result in ground faults in therest of the plant), such as may be useful for integrating powerelectronics of the second filter assembly 206 and the electrolyzer 208.In instances in which the second filter assembly 206 and theelectrolyzer 208 operate on the same DC voltage, the power electronics275 may be a single integrated unit (e.g., a single DC/DC converter). Ininstances in which the second filter assembly 206 and the electrolyzer208 operate on a different DC voltages, the power electronics 275 mayinclude plural DC/DC converters

In some instances, the power electronics 275 may be useful fordiagnosing degradation of second filter assembly 206, the electrolyzer208, or a combination thereof. For example, the power electronics 275may include impedance monitoring of electrochemical cells of the secondfilter assembly 206 and/or the electrolyzer 208 to trigger reductions incurrent and/or promote achieving long component life (e.g., bytriggering one or more recovery processes such as reversal of polarityalong the common DC bus 274 through actuation by the controller 244).For example, the power electronics 275 may be operable to generateripple current for impedance measurement and to monitor impedance of theelectrolyzer 208. The power electronics 275 and the controller 244 whichcontrols the power electronics 275 may be able to then conduct fastFourier transform analysis to derive the frequency and amplitude ofcomponent impedance values.

Other equipment used to operate the system 200 may be coupled to thecommon DC bus 274 to receive power. For example, in some cases, pumpequipment 276 used for balance of plant pumping and compression may becoupled to the common DC bus 274. For example, the pump equipment 276may comprise fluid pumps, fans and/or blowers which operate onalternating current (AC). In this configuration, the pump equipment 276may be connected to the common DC bus 274 via one or more DC/ACinverters 282.

The power source 215, the battery 273, and the generator 267 may each beelectrically coupled to the input side of the common DC bus 274 and toone another. For example, the power source 215 may include one or moreof an AC grid power source 277, an AC renewable power source 278 (e.g. awind turbine), and/or a DC renewable power source 279 (e.g., aphotovoltaic array). In instances, in which the power source 215includes the DC renewable power source 279, the generator 267 and the DCrenewable power source 279 may each be in electrical communication withthe battery 273 and with a DC/DC converter 280 such that each source ofpower may be directed to the battery 273 and/or to the common DC bus 274as needed to meet power demands. The AC grid power source 277 and the ACrenewable power source 278 (e.g. a wind turbine) may be electricallyconnected to the common DC bus 274 through one or more additional AC/DCinverters 281.

In certain implementations, the controller 244 may be configured toauctioneer power at the common DC bus 274 to direct available powerproportionally at least to the second filter assembly 206 and theelectrolyzer 208. This may facilitate optimal plant operation within thebudget of available power. Further, or instead, the controller 244 mayallocate power for water purification flushing and other periodic plantactivities and accommodate such power allocation by cutting back powerto the electrolyzer 208.

The above systems, devices, methods, processes, and the like may berealized in hardware, software, or any combination of these suitable forthe control, data acquisition, and data processing described herein.This includes realization in one or more microprocessors,microcontrollers, embedded microcontrollers, programmable digital signalprocessors or other programmable devices or processing circuitry, alongwith internal and/or external memory. This may also, or instead, includeone or more application specific integrated circuits, programmable gatearrays, programmable array logic components, or any other device ordevices that may be configured to process electronic signals. It willfurther be appreciated that a realization of the processes or devicesdescribed above may include computer-executable code created using astructured programming language such as C, an object orientedprogramming language such as C++, or any other high-level or low-levelprogramming language (including assembly languages, hardware descriptionlanguages, and database programming languages and technologies) that maybe stored, compiled or interpreted to run on one of the above devices,as well as heterogeneous combinations of processors, processorarchitectures, or combinations of different hardware and software. Atthe same time, processing may be distributed across devices such as thevarious systems described above, or all of the functionality may beintegrated into a dedicated, standalone device. All such permutationsand combinations are intended to fall within the scope of the presentdisclosure.

Embodiments disclosed herein may include computer program productscomprising computer-executable code or computer-usable code that, whenexecuting on one or more computing devices, performs any and/or all ofthe steps of the control systems described above. The code may be storedin a non-transitory fashion in a computer memory, which may be a memoryfrom which the program executes (such as random access memory associatedwith a processor), or a storage device such as a disk drive, flashmemory or any other optical, electromagnetic, magnetic, infrared orother device or combination of devices. In another aspect, any of thecontrol systems described above may be embodied in any suitabletransmission or propagation medium carrying computer-executable codeand/or any inputs or outputs from same.

The method steps of the implementations described herein are intended toinclude any suitable method of causing such method steps to beperformed, consistent with the patentability of the following claims,unless a different meaning is expressly provided or otherwise clear fromthe context. So, for example performing the step of X includes anysuitable method for causing another party such as a remote user, aremote processing resource (e.g., a server or cloud computer) or amachine to perform the step of X. Similarly, performing steps X, Y and Zmay include any method of directing or controlling any combination ofsuch other individuals or resources to perform steps X, Y and Z toobtain the benefit of such steps. Thus, method steps of theimplementations described herein are intended to include any suitablemethod of causing one or more other parties or entities to perform thesteps, consistent with the patentability of the following claims, unlessa different meaning is expressly provided or otherwise clear from thecontext. Such parties or entities need not be under the direction orcontrol of any other party or entity, and need not be located within aparticular jurisdiction.

It will be appreciated that the methods and systems described above areset forth by way of example and not of limitation. Numerous variations,additions, omissions, and other modifications will be apparent to one ofordinary skill in the art. In addition, the order or presentation ofmethod steps in the description and drawings above is not intended torequire this order of performing the recited steps unless a particularorder is expressly required or otherwise clear from the context. Thus,while particular embodiments have been shown and described, it will beapparent to those skilled in the art that various changes andmodifications in form and details may be made therein without departingfrom the scope of the disclosure.

What is claimed is:
 1. A method, comprising: providing raw water into afirst filter assembly to remove solids from the raw water to form afiltrate; providing the filtrate from the first filter assembly into asecond filter assembly to electrochemically or electrically removeionics from the filtrate to form purified water; providing the purifiedwater to an electrolyzer to generate hydrogen by electrolyzing thepurified water; and pressurizing the hydrogen generated by theelectrolyzer in a hydrogen pump.
 2. The method of claim 1, furthercomprising recirculating the pressurized hydrogen to the electrolyzer.3. The method of claim 1, wherein the second filter assembly includes anelectrodialysis cell, an electrooxidation cell, or a combinationthereof.
 4. The method of claim 1, further comprising providing thehydrogen generated by the electrolyzer to an ammonia synthesis reactorto produce ammonia.
 5. The method of claim 1, further comprising storingthe hydrogen generated by the electrolyzer in a hydrogen storage vessel.6. The method of claim 1, further comprising providing the hydrogengenerated by the electrolyzer to a generator.
 7. A method, comprising:providing power from a power source to an electrolyzer in a hydrogenproduction system to electrolyze purified water to generate hydrogen;storing at least a portion of the generated hydrogen in a hydrogeninventory; monitoring power availability from the power source;comparing a power requirement of the hydrogen production system to thepower availability from the power source; and generating power by agenerator fueled by hydrogen from the hydrogen inventory if the powerrequirement is less than the power availability.
 8. The method of claim7, further comprising providing a flow of purified water from anelectrically energizable filter assembly to a water inventory.
 9. Themethod of claim 7, wherein the power source comprises a renewable powersource.
 10. The method of claim 7, wherein the generator comprises afuel cell power generator.
 11. The method of claim 7, wherein generatingpower by the generator further comprises providing a flow of purifiedwater from the water inventory to the generator.
 12. The method of claim7, wherein monitoring power availability from the power source includesdetecting an outage.
 13. The method of claim 7, further comprisingproviding the generated power to the electrolyzer to continue togenerate the hydrogen.
 14. The method of claim 7, further comprisingdetermining a power requirement for the hydrogen production systembefore the comparing step.
 15. The method of claim 7, further comprisingshutting down the hydrogen production system.